The present invention relates generally to communication systems. More specifically, the invention relates to assigning communication channels in a wireless communication system.
The use of wireless communication systems for the transmission of digital data is becoming more and more pervasive. In a wireless system, the most precious resource in terms of cost and availability is typically the wireless link itself. Therefore, one major design goal in designing a communication system comprising a wireless link is to efficiently use the available capacity of the wireless link.
In a time division multiple access (TDMA) system, which also uses frequency division, a frequency channel is defined by a center frequency and a time slot. Within a frequency channel, each remote unit has its own remote unit ID number and is assigned resources in round robin fashion. Thus, if three TDMA frequency channels are created, each of the remote units assigned to the frequency channel transmits approximately one third of the time.
In a typical system, the hub station dictates which channel the remote unit uses for communicating back to the hub station. The communication from the remote unit to the hub station is termed a xe2x80x9creverse linkxe2x80x9d whereas communication from the hub station to the remote unit is termed a xe2x80x9cforward linkxe2x80x9d.
In a conventional wireless system, if the remote unit needs to send data over a reverse link, it requests a channel from the hub station. In response to all of the remote unit channel requests, the hub station then generates a broadcast message that is sent to all of the remote units and provides each of their frequency channel assignments. A typical broadcast message includes the frequency, time slot and remote unit ID number of each remote unit that has indicated it has data to send.
Each remote unit receives the broadcast message, and determines its proper frequency and channel by waiting until its remote unit ID number is broadcast. However, this type of system requires a tremendous amount of information to be sent from the hub station to the remote units in every broadcast message. This is disadvantageous because all of the broadcast message overhead prevents user data from being sent through the system. Thus, there is a need in the art for a more efficient way of assigning remote unit channels in a wireless communication system.
One embodiment of the invention is a method for assigning reverse link resources to a plurality of remote units, comprising the steps of: receiving at a hub station requests for reverse link resources from a plurality of remote units; determining an assignment of reverse link channels to the plurality of remote units; creating a message designating the assignment wherein the message designates explicitly a set of remote unit identifiers corresponding to the plurality of remote units and implicitly designates a channel according to the location of the identifier within the message; and broadcasting the message to the plurality of remote units.
Embodiments of the invention also provide a remote unit method for allocating reverse link resources in a multiple access communication system, comprising the steps of: requesting reverse link resources from a hub station; receiving a broadcast message assigning reverse link resources to a plurality of remote units wherein said broadcast message designates explicitly a plurality of remote unit identifiers and implicitly designates a channel according to its location within the message; and transmitting a signal over a reverse link channel corresponding to a location of the remote unit identifiers within the broadcast message.
Another embodiment of the invention is an apparatus which assigns reverse link resources to a plurality of remote units, comprising: means for receiving at a hub station requests for reverse link resources from a plurality of remote units; means for determining an assignment of reverse link channels to the plurality of remote units; means for creating a message designating said assignment wherein the message designates explicitly a set of remote unit identifiers corresponding to the plurality of remote units and implicitly designates a channel according to the location of the identifier within the message; and means for broadcasting the message to the plurality of remote units.
Embodiments of the invention also provide an apparatus which allocates reverse link resources in a multiple access communication system, comprising: means for requesting reverse link resources from a hub station; means for receiving a broadcast message at the hub station assigning reverse link resources to a plurality of remote units wherein the broadcast message designates explicitly a plurality of remote unit identifiers and implicitly designates a channel according to its location within the message; and means for transmitting a signal over a reverse link channel corresponding to a location of the remote unit identifiers within the broadcast message.
Yet another embodiment of the invention is a system for allocating reverse link resources in a multiple access communication system, comprising: a hub station for receiving requests for reverse link resources from a plurality of remote units; determining an assignment of reverse link channels to the plurality of remote units; creating a message designating the assignment wherein the message designates explicitly a set of remote unit identifiers corresponding to the plurality of remote units and implicitly designates a channel according to the location of the identifier within the message; broadcasting the message to the plurality of remote units; a remote unit for requesting reverse link resources from the hub station; receiving a broadcast message assigning reverse link resources to a plurality of remote units wherein the broadcast message designates explicitly a plurality of remote unit identifiers and implicitly designates a channel according to its location within the message; and transmitting a signal over a reverse link channel corresponding to a location of the remote unit identifier within the broadcast message. Preferably, the reverse link comprises a satellite link. In one aspect of a preferred embodiment, not all of the channels are assigned. Preferably, the channels are assigned in order and the message is terminated when all of the reverse link resources are assigned. Alternatively, a dummy remote unit identifier is sent in unassigned channel locations.